<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>

    #d1{
      width: 100px;height: 100px;border: 1px solid red;
      /*单独某一个方向赋值*/
     /* margin-left: 100px;
      margin-top: 50px;
      margin-bottom: 30px;
      margin-right: 50px;*/
      margin: 50px;/*四个方向添加外边距*/
      margin: 50px 100px;/*上下50  左右100*/
      margin: 10px 20px 30px 40px;/*上右下左 顺时针赋值*/
    }
    #d2{
      width: 100px;height: 100px;border: 1px solid red;
      margin-top: 50px;
    }
    #big{
      width: 200px;height: 200px;
      background-color: green;
      overflow: hidden;/*解决外边距塌陷导致的粘连问题*/
    }
    #big>div{
      width: 50px;height: 50px;
      background-color: red;
      margin-left: 50px;
      margin-top: 100px;
    }
    span{border: 1px solid blue}
    /*行内元素上下外边距无效*/
    #s1{margin-right: 50px}
    /*左右相邻彼此添加外边距,两者相加*/
    #s2{margin-left: 30px}
  </style>
</head>
<body>
<span id="s1">span1</span><span id="s2">span2</span>
<div id="big">
  <div></div>
</div>
<div id="d1">div1</div>
<div id="d2">div2</div>
</body>
</html>